Wireless Network POJ - 2236

#include<iostream>
#include<cmath>
using namespace std;
const int N=1010;
int dx[N],dy[N];
int p[N];
int repair[N];
int n;
int d;
double get(int a,int b)
{
    return sqrt(double(dx[a]-dx[b])*(dx[a]-dx[b])+(dy[a]-dy[b])*(dy[a]-dy[b]));
}
int find(int x)
{
    if(p[x]!=x)
        p[x]=find(p[x]);
    return p[x];
}
int main()
{
    cin>>n>>d;
    for(int i=1;i<=n;i++)
        p[i]=i;
    for(int i=0;i<n;i++)
        cin>>dx[i]>>dy[i];
    char cmd[2];
    int len=0;
    int p1;
    int q;
    while(cin>>cmd)
    {
        //如果是维修 
        if(cmd[0]=='O')
        {
            cin>>p1;
            p1--;
            //存起来 
            repair[len++]=p1;
            //每次维修，都和之前已经维修好的合并 
            for(int i=0;i<len-1;i++)
                if(repair[i]!=p1&&get(repair[i],p1)<=double(d))
                    p[find(repair[i])]=find(p1);
        }
        else if(cmd[0]=='S')
        {
            cin>>p1>>q;
            p1--,q--;
            if(find(p1)==find(q))
                cout<<"SUCCESS"<<endl;
            else
                cout<<"FAIL"<<endl;
        }
    }
    return 0; 
}